Muffler including tapered inlet nozzle with tapered opening



Aug. 8, 1950 R. C. BAIRD MUFFLER INCLUDING TAPERED INLET NOZZLE Filed May 19, 194'? l'op w h E 5 a M 33 5' 36k 32 4 as E 40 56 a? Barnaua 830100 INVENTOR.

Patented Aug. 8, 1950 MUFFLERw INCLUDING TAPERED INLET NOZZLE WITH. TAPERED OPENING Raymond G. Baird, Los Angeles, Calif.., assignor to The Floor Corporation, Ltd., Los Angeles, Calif., a corporation of California Application May19; 1947; Serial'No. 748,961.

'7' Claims. 1 This invention hasv to do generally with the elimination of-sound, vibratory and other effects caused by the flow o undulaiflng; characteristics of. gas streams; the. invention having particular applicability-for the elimination of such ei'lectsin.

equipment such as muiilers or dampers, intendedto.suppress either or bothgaudible andsub-audible undulation frequencies in the gas.

The invention is aimed primarilyat the elimination of vibrations and: sounds created or existing at the point of discharge of the gas from a conduit as. from: the; inlet pipe of a muffler or damper. Considering enginemufflers. as: typical, there exists. a tendency for resonance to be created in the exhaust pipe itself by reason of, abrupt discontinuity in theorem-sectional area: of the pipeat the point of: gasdischarge intothe muffler chamber or shell. Inlits majoraspectsthe invention has forits object to reduce the mag nitude of reflectedacousticalenergv atthemuliier inlet to a degree eliminating the; disturbances normally created by such energy, and. inso doing, to materially improvethe ovenallzefficiency of the mufller asa whole.

Briefly, the invention is in the nature of an acoustic discontinuity diffuser comprising an appropriate body structure forming a gas passage, of, gradually decreasing cross-sectional area from: which the gas. is released through one or more openings extending longitudinally of thepassageand. havinggprogressiyely increasing size onwidth. A-ccoustically speaking. injector of this type affords to the gas flowingrthrougha passage hav the stated characteristics; a progressively decreasing impedancewvhich may. approach zero toward the end: of the passage. Exhaust gases may leave the passage from any location. along its length in a quantity which is small as com-. pared with the gas remaining and advancing in the passage beyond such. location. Thusthe ratio of the gas escape tothe continued flow in the passagemay increasefrom zero at the entrance-of the injector, to a maximum at itsend. A result of: major significance is: that the energy reflected by the cross-sectional area variances ofthe injector is so small relative to that of'the incident gas stream, that there is little tendency for the creation of pipe resonance. In addition, the inn oremental energy reflections produced along the gas escape openings are shifted in phase relathe injector tend also to inhibit chamber resow nance. 7

In: suppressing. shock resonance of the mufller because of the explosive pulses contained in. the exhaust gas, the injector acts. as a filter whereby the energy. at any point along. the pulse wave is. distributed lengthwise of the injector so that path differences in the muliler chamber result in phase shift. The consequent filtering or pulse smoothing effect suppresses shock waves of. such magnitude as to cause mechanical. vibration ofthe muffier shell. Advantage is. taken of= this further filtering effect in that alteration. of the incident wave characteristics facilitates the ultimate sound muflling tobe, accomplished.

Further details of the contemplated injector, as well as its association: with an exhaust gas mufller, will be understoodfrom. the following detailed description ofcertain illustrative embodi-. mentsof the invention, reference being had throughout the description, in the accompanying drawing, in which;

Fig. 1 is ayiew showing the muiiler in vertical, Section; I

Fig. 2 is. a cross-section on line 2.- -2 of. Fig. 1;,

Figs. 3v and 4 are sectional views illustrating. variational forms of the invention; and

Fig. 5 is an-enlarged cross-section on. line 5 -5, of Fig. 3.

While specifically adaptable to mufflers having. any desired gas inlet and. outlet arrangement, 1; have selected as illustrativea vertical type mute fler having a shell I0. provided with a. lower, side inlet II and atop outlet l2. The shell it} contains a transverse partition; l3 dividing. the

' shell interiorinto an, inlet chamber l4 and a com.-

municating chamber 15 within which undulations. remaining in the as. stream, flowing from chamber I4, are eliminated or dampened by ap-.

propriate sound. absorbing means, of which the later described mufller structure is to be regarded as typical.

Chamber 14 contains the acoustical diffuser. generally indicated at l6, which may have any of, various forms possessing: the characteristic of presenting to the entering gas stream an elongated passage of progressively decreasing O1OSS.-- sectional area, from which the gas is released intothe chamber through one or more slot-like openings of progressively increasing width or size. As illustrative, the diffuser may comprise a hollow, channel shaped shell I! connected by adaptor l-8 with the gas inlet line l9. As illustrated in Fig. 2-,, the shell-extends circularly within the cham her and forms with themufller shell l0. apassage,

20 which progressively diminishes from a maximum cross-sectional area at its inlet end 2|, to a minimum cross-sectional area at the passage terminal 22. The channel flanges 23 are spaced at 24 from the shell Hi to form openings whose width progressively increases as the passage area decreases, and through whichthe gas is progressively released'into the chamber l4 along the course of its flow within the channel passage. As a result the gas is prevented by its diffused re- 4 acoustical discontinuity difluser within said chamber comprising a body communicating with said inlet and containing an elongated tapered lease from creating impulses which might other--= wise result from discharge through an ordinary open end conduit.

Fig. 3 illustrates a variational form of diffuser '25 comprising a hollow shell 26 receiving gas from the inlet or adapter 21 and having a pair of symmetrical branches 2611 whose cross-sectional areas progressively reduce toward the ends of the branches welded to the shell H1 at 28. The edges of the difiuser sides or flanges 29 are spaced from a V-shaped baflie 30 to form the gas discharge openings 3|, the width of which progressively increases toward the branch extremities, as illustrated.

Fig. 4 shows a further variational form of diffuser adapted to be positioned vertically within a .mufiler shell S having a lower side gas inlet 34. Here the difiuser may comprise a circular or square cross-section hollow shell 32 connected by adapter 33 with the inlet 34, and having a pair of gas escape branches 35 and 36 tapering outwardly to define passages of progressively de: creasing cross-sectional area. As illustrated, the branches 35 and 36 may have different lengths. The gas escapes from the branch passages through progressively widening slots or openings 3'! formed by splitting the branch shells longitudinally.

Referring to Fig. l, chamber l5 contains a plurality of perforated tubes 38, 39 and 40 spaced concentrically within the shell III to define between the tubes annular passages 4l and 42 through which the gas flows in the courses indicated by the arrows. Tubes 39 and 40 have a top closure 43 which requires the gas flowing from chamber [4 through tube 38 to reverse its flow in passing downwardly through space 4 I, and again into space 42 from which the gas is released through the perforations 44 into chamber i5 the gas thence of course flowing through the outlet 'l2. Simultaneously with its flow longitudinally through passages 4i, and 42, the gas is released transversely thereinto through the perforations in the tubes 38 and 39, all to the end that the resulting divisions and co-mingling of the gas along its course of flow produces mutfiing efiects to a high degree. Structural and functional details of this type of concentric perforated tube muiiier, are more particularly dealt with in Patent No. 2,363,236 issued November 21, 1944, to P. E. Fluor on Air-Cooled Muiiler.

' I claim:

l. A gas undulation damper including a shell containinga chamber having an inlet, and an acoustical discontinuity diiluser within said chamber comprising a body communicating with said'inletand'containing an elongated tapered passage of progressively decreasing cross-sectional area in'the direction of the gas flow therethroughand from which the gas escapes through a'discharge opening of progressively increasing size coextensive withsaidtapered passage and defined by straight edges of said body intersecting at a point. r 2 A gas undulation damper, including a shell containing a chamber having an inlet, and an passage of progressively decreasing cross-sectional area in the direction of the gas flow therethrough and from which the gas escapes through a slot-like gasdischarge opening of gradually and progressively increasing width in the direction of gas flow through said passage said body being open for straight line flow of the gases at the discharge end of said passage and said discharge opening being coextensive with said tapered passage and defined by straight edges of said body intersecting at a point.

3. A gas undulation damper including a shell containing a chamber having an inlet, and an acoustical discontinuity difiuser within said chamber comprising a body communicating with said inlet and containing an elongated tapered passage of progressively decreasing cross-sectional area in the direction of the gas flow therethrough and from which the gas escapes through a plurality of slot-like discharge openings at op-' posite sides of said passage and having progressively increasing width in the direction of gas flow through the passage, said discharge open' ings being coextensive with said tapered passage and defined by straight edges of said body interto form therewith a slot-like gas discharge 'open-' ing of gradually and progressively increasing width in the direction of'gas flow through said passage, said opening being coextensive with said tapered passage and being defined by straight edges intersecting at a point.

5. A gas undulation damper including a cylindrical shell containing a chamber having an inlet, and an acoustical discontinuity diffuser within said chamber comprising a circularly curved body communicating with said inlet and con-' taining an elongated tapered passage of progressively decreasing cross-sectional area in the direction of the gas flow therethrough, said body being spaced from said shell to form with its cylindrical wall a slot-like gas discharge opening of gradually and progressively increasing width in the direction of gas flow through said passage, said opening being coextensive with said tapered passage and being defined by straight edges intersecting at a point.

6. A gas undulation damper including a shell containing a chamber having an inlet, and an acoustical discontinuity diffuser within said chamber comprising a hollow body shell communicating with said inlet and tapered therefrom to contain an elongated tapered passage of REFERENCES CITED The following references are of record in the file of this patent:

Number Number 6 UNITED STATES PATENTS Name Date Kull May 27, 1902 Gibson Aug. 30, 1910 Reed Sept. 18, 1923 Bourne Apr. 29, 1930 Harley Aug. 15, 1933 Mordt Mar. 9, 1937 FOREIGN PATENTS Country Date Great Britain Feb. 5, 1931 

